Linkage Groups of Protein-Coding Genes in Western Palearctic Water Frogs Reveal Extensive Evolutionary Conservation

Among progeny of a hybrid (Rana shqiperica X R. lessonae) X R. lessonae, 14 of 22 loci form four linkage groups (LGs): (1) mitochondrial aspartate aminotransferase, carbonate dehydratase-2, esterase 4, peptidase D; (2) mannosephosphate isomerase, lactate dehydrogenase-B, sex, hexokinase-1, peptidase B; (3) albumin, fructose-biphosphatase-1, guanine deaminase; (4) mitochondrial superoxide dismutase, cytosolic malic enzyme, xanthine oxidase. Fructose-biphosphate aldolase-2 and cytosolic aspartate aminotransferase possibly form a fifth LG. Mitochondrial aconitate hydratase, α-glucosidase, glyceraldehyde-3-phosphate dehydrogenase, phosphogluconate dehydrogenase, and phosphoglucomutase-2 are unlinked to other loci. All testable linkages (among eight loci of LGs 1, 2, 3, and 4) are shared with eastern Palearctic water frogs. Including published data, 44 protein loci can be assigned to 10 of the 13 chromosomes in Holarctic Rana. Of testable pairs among 18 protein loci, agreement between Palearctic and Nearctic Rana is complete (125 unlinked, 14 linked pairs among 14 loci of five syntenies), and Holarctic Rana and Xenopus laevis are highly concordant (125 shared nonlinkages, 13 shared linkages, three differences). Several Rana syntenies occur in mammals and fish. Many syntenies apparently have persisted for 60-140 X 10(6) years (frogs), some even for 350-400 X 10(6) years (mammals and teleosts).     

Genetic differences in glucose phosphate isomerase activity among mouse embryos

We have compared mouse embryos of three heterozygous, congenic genotypes (with high, medium and low levels of oocyte-coded glucose phosphate isomerase (GPI-1) activity respectively) to test whether 1) the survival time of oocyte-coded GPI-1 activity in the early embryo is affected by its activity level in the oocyte and 2) whether embryo-coded GPI-1 is detected earlier in embryos that inherit low levels of oocyte-coded GPI-1. The oocyte-coded GPI-1 was entirely GPI-1A allozyme in the high and medium groups but was the less stable GPI-1C allozyme in the low group. We determined total GPI-1 activity and the ratio of different GPI-1 allozymes in early embryos and calculated the activity of oocyte-coded and embryo-coded GPI-1. In all three groups, the oocyte-coded enzyme activity remained at a more or less constant level for the first 21 1/2 days. Some oocyte-coded GPI-1 remained in 4 1/2 day embryos from the high and medium groups but was gone by 5 1/2 days. Very little remained in 4 1/2 day embryos that inherited low levels of a less stable form of the enzyme (GPI-1C allozyme). Despite a 4- to 5-fold difference in initial oocyte-coded GPI-1 activity, no differences were seen among the three genotypically distinct groups of embryos in the time of activation of the embryonic Gpi-1s genes. The embryo-coded GPI-1 was first detectable in 3 1/2 day compacted morulae in all three groups. The level of oocyte-coded GPI-1, in the high group, when embryo-coded GPI-1 was first detected was higher than the level in the low group at any stage prior to detection of embryo-coded GPI-1.(ABSTRACT TRUNCATED AT 250 WORDS)     

Alcohol Dehydrogenase in the Diploid Plant STEPHANOMERIA EXIGUA (Compositae): Gene Duplication, Mode of Inheritance and Linkage

Study of the biochemical genetics of alcohol dehydrogenase (ADH) in the annual plant Stephanomeria exigua (Compositae) revealed that the isozymes are specified by a small family of tightly linked structural genes. One set of ADH isozymes (ADH-1) was induced in roots by flooding, and was also expressed in thickened unflooded tap roots, stems, ovaries and seeds. As in other plants, the enzymes are dimeric and form homo- and heterodimers. An electrophoretic survey of ADH-1 phenotypes in two natural populations revealed seven different ADH-1 homodimers in various phenotypes having one to eight enzyme bands. Genetic analysis of segregations from crosses involving 59 plants showed that the ADH-1 isozymes are inherited as a single Mendelian unit, Adh1. Adh1 is polymorphic for forms that specify one, two, or three different ADH-1 subunits (which combine to form homo- and heterodimers), and are expressed co-dominantly in all genotypic combinations. Staining intensity of enzymes extracted from various homozygous and heterozygous plants indicated that the different subunit types specified by Adh1 are produced in approximately equal amounts. These observations suggest that Adh1 is a compound locus consisting of one to several tightly linked (0 recombinants among 579 testcross progeny), coordinately expressed structural genes. The genes in the two triplications also occur in various duplicate complexes and thus could have originated via unequal crossing over. The ADH-2 isozyme found in pollen and seeds is apparently specified by a different gene, Adh2. Adh1 and Adh2 are tightly linked (0 recombinants among 81 testcross progeny).     

Genetic linkage between the loci for phosphohexose isomerase (PHI) and a serum protein (Xk) in horses

Genetic linkage between the equine loci for phosphohexose isomerase (PHI) and serum Xk protein was demonstrated by means of segregation data from three sire families. The recombination frequency was estimated from pooled data to be 0.23 +/- 0.02; a significant heterogeneity between sires for estimates of the recombination frequency was observed. No indication of linkage was detected between Xk and 14 other blood marker loci. Linkage between the Xk locus and the locus for soluble malic enzyme (ME1) has recently been reported in horses. An equine linkage group designated LG IV comprising the three loci ME1, PHI, and Xk has thus been established. The possibility that the linkage between PHI and Xk is homologous to the linkage between the loci for PHI and a serum postalbumin (PO-2) in pigs was discussed.     

Genetic linkage between the loci for phosphohexose isomerase (PHI) and a serum protein (Xk) in horses

Genetic linkage between the equine loci for phosphohexose isomerase (PHI) and serum Xk protein was demonstrated by means of segregation data from three sire families. The recombination frequency was estimated from pooled data to be 0.23 ± 0.02; a significant heterogeneity between sires for estimates of the recombination frequency was observed. No indication of linkage was detected between Xk and 14 other blood marker loci. Linkage between the Xk locus and the locus for soluble malic enzyme ( ME1 ) has recently been reported in horses. An equine linkage group designated LG IV comprising the three loci ME1, PH1 , and Xk has thus been established. The possibility that the linkage between PH1 and Xk is homologous to the linkage between the loci for PHI and a serum postalbumin (PO-2) in pigs was discussed.     

Differential regulation of duplicate alcohol dehydrogenase genes in Drosophila mojavensis

These studies report the existence of multiple forms of alcohol dehydrogenase in extracts of Drosophila mojavensis. The existence of these forms can be best explained by the hypothesis of a duplication for the Adh locus in D. mojavensis. Electrophoretic variants at each locus have been identified and crosses between individuals carrying alternative alleles at each locus result in F1 progeny with six bands of ADH. This pattern is consistent with these individuals being heterozygous at two loci. The loci have been named Adh-1 and Adh-2. Examination of the isozyme content during development shows that the two Adh genes are not coordinately controlled but have separate developmental programs. In embryos and first and second instar larvae only Adh-1 is expressed. At about the time of the second molt Adh-2 expression commences in some of the same cells that previously expressed and continue to express Adh-1. This is evidenced by the existence of an interlocus heterodimer in third instar larvae. Both genes are expressed throughout pupation. Shortly after emergence Adh-1 expression declines. In mature males only ADH-2 is present. In mature females both Adh-1 and Adh-2 are expressed but not in the same cells since the interlocus heterodimer is absent. Examination of specific tissues reveals that most of the larval ADH is found in fat body cells and as in most tissues of third instar larvae both Adh-1 and Adh-2 are expressed. The single exception appears to be larval gut which contains ADH-1 but little if any ADH-2. In mature males and female flies all ADH containing tissues have only ADH-2. However, mature ovaries contain substantial quantities of ADH-1 which is apparently deposited into eggs. Given the extensive amount of available information on the Adh gene-enzyme system of D. melanogaster and the tools that can be applied to the analysis of homologous systems, the ADH duplication of D. mojavensis, and its regulation may be a useful one for studying differential gene regulation in specific cell types.     

Assignment of the gene for lactic dehydrogenase A to mouse chromosome 7 using mouse-human hybrids

We have studied somatic cell hybrids between either mouse peritoneal macrophages or spleen cells and HT-1080-6TG human fibrosarcoma cells for the expression of mouse lactic dehydrogenase A (LDH-A). The hybrids were also studied for the expression of mouse glucose phosphate isomerase (GPI-1), the gene for which has been assigned to chromosome 7. Concordant segregation of the expression of mouse GPI-1 and LDH-1 was observed in 61 independent hybrid clones. These results indicate that the gene coding for LDH-A is located on mouse chromosome 7.     

Evolution of immunoglobulin light chain genes: analysis of Xenopus IgL isotypes and their contribution to antibody diversity.

The amphibian Xenopus laevis expresses several types of immunoglobulin light chain (IgL). cDNA clones for two IgL isotypes, C sigma 1 and C sigma 2, were analysed. C sigma is expressed in spleen and mitogen-stimulated B cells, like another Xenopus IgL type, termed C rho. C sigma shares less than 33% residues with C rho or with CL regions of shark, chicken and mammals. This suggests that C sigma diverged from a common ancestor of CL regions before or at the emergence of amphibians. Two families of VL elements, V sigma 1 and V sigma 2 are associated with C sigma (but not with C rho). They rearrange to their own set of JL elements, J sigma 1 and J sigma 2, which are poorly related to other J elements of the Ig gene family. The Xenopus genome contains a few V sigma 2 and multiple V sigma 1 elements (comparable with mammalian V kappa), but only two C sigma genes. Thus, the organization and expression of Xenopus IgL loci are apparently similar to mammalian IgL loci but different from shark and chicken IgL loci. Only a few VL elements are expressed, since cDNA clones show extensive sharing of CDR1 and CDR2 sequences; some clones differ only in CDR3. Rearranging VL and JL elements increases CDR3 diversity in both V sigma families, but abortive rearrangements are frequent in V sigma 1 regions. The very poor heterogeneity of expressed VL elements therefore appears to limit antibody diversity in Xenopus.     

Developmental profile of glucose phosphate isomerase allozymes in parthenogenetic and tetraploid mouse embryos.

Glucose phosphate isomerase (GPI) allozymes were compared in eggs and embryos of the mouse strains C57BL/6-JHan (GPI-1BB) and 129/Sv (GPI-1AA) under different experimental conditions. The quantitative differences in eggs of the two strains disappeared by the blastocyst stage at day 4 to 5, both in fertilized and diploid parthenogenetic embryos. The degree of degradation of oocyte-coded enzyme molecules and the activation of the embryonic genome for GPI appeared to be equivalent in parthenogenetic embryos from heterozygous females when only one or other maternal allele type remained in the egg after meiosis. Also in tetraploid embryos, generated by electrofusion of homozygous fertilized eggs from the two strains, both genomes seemed to be activated at the same time at day 4; here, however, the GPI-1BB allozyme remained predominant up to day 6.     

Evolution of duplicate genes in a tetraploid animal, Xenopus laevis

To understand the evolution of duplicate genes, we compared rates of nucleotide substitution between 17 pairs of nonallelic duplicated genes in the tetraploid frog Xenopus laevis with rates between the orthologous loci of human and rodent. For all duplicated X. laevis genes, the number of synonymous substitutions per site (dS) was greater than the number of nonsynonymous substitutions per site (dN), indicating that these genes are subject to purifying selection. There was also a significant positive correlation (r = 0.915) between dN for the X. laevis genes and dN for the mammalian genes, suggesting that, at the amino acid level, the X. laevis genes and the mammalian genes are under similar constraints. Results of relative-rate tests showed nearly equal rates of nonsynonymous substitution in each copy of the X. laevis genes; apparently there are similar constraints on both copies. No correlation was found between dS for the X. laevis genes and dS for the mammalian genes. There was a significant positive correlation both between members of pairs of duplicated X. laevis genes (r = 0.951) and between human and rodent orthologues (r = 0.854) with respect to third- position G+C content but no such relationship between the X. laevis genes and either of their mammalian orthologues. The results indicate that both copies of a duplicate gene can be subject to purifying selection and thus support the hypothesis of selection against all genotypes containing a null allele at either of two duplicate loci.      

Chromosomal location of isozyme and seed storage protein genes in Dasypyrum villosum (L.) Candargy

Summary The zymogram phenotypes of glucose-phosphate isomerase (GPI), alcohol dehydrogenase-1 (ADH-1), glutamate oxaloacetate transaminase (GOT), superoxide dismutase (SOD), lipoxygenase (LPX), esterase (EST) and the banding patterns of gliadin and glutenin seed storage proteins were determined for Triticum aestivum cv. Chinese Spring (CS), Dasypyrum villosum, the octoploid amphiploid T. aestivum cv. Chinese Spring D. villosum (CS × v) (2n=8x=56; AABBDDVV), and for five CS-D. villosum disomic addition lines. The genes Gpi-V1, Adh-V1, Got-V2, and Sod-V2 coding for GPI-1, ADH-1, GOT-2, and SOD-2 isozymes were located in D. villosum on chromosome 1V, 4V, 6V, and 7V, respectively. Genes coding for gliadin- and glutenin-like subunits are located in D. villosum chromosomes 1V. There are no direct evidence for chromosomal location of genes coding for GOT-3, EST-1 and LPX-2 isozymes. The linkage between genes coding for glutenin-like proteins and GPI-1 isozymes in chromosome 1V is evidence of homoeology between chromosome 1V and the chromosomes of homoeologous group 1 in wheat.Research supported by the National Research Council (Italy) and National Science Foundation (USA). International cooperative project, Grant No. 85.01504.06 (CNR)     

Intraspecific red cell enzyme variation in the pigtailed macaque (Macaca nemestrina)

The erythrocytes of 350 pigtailed macaques (Macaca nemestrina) were examined for electrophoretic variation of hemoglobin and 26 enzymes. Seven enzymes showed variation in more than 1% of individuals: phosphoglucose isomerase, phosphoglucomutase-1, soluble NADP-dependent isocitric dehydrogenase, peptidase A, peptidase C, 2,3-diphosphoglycerate mutase, and acid phosphatase. Variation with lesser frequency was found in soluble glutamic-oxalacetic transaminase, phosphoglycerate kinase, lactic dehydrogenase, and hemoglobin. Only eight samples were tested for esterase D, and one of these had a variant phenotype. Enzymes with no clear variation were adenylate kinase, adenosine deaminase, phosphofructokinase, hexokinase, pyruvate kinase, glyceraldehyde 3-phosphate dehydrogenase, aldolase, phosphoglycerate mutase, phosphopyruvate hydratase (enolase), phosphoglucomutase-3, and superoxide dismutase. There was father-to-son transmission of PGI, PGM-1, peptidase C, 6PGD, 2,3-DPGAM, NADP-ICD, and acid phosphatase variants, suggesting that these loci are autosomal as in man.     

Linkage of two enzyme loci in the fish genus Poecilia (Teleostei:Poeciliidae).

The linkage of loci coding for glucose-6-phosphate dehydrogenase (G6PD) and phosphogluconate dehydrogenase (PGD) is described in fish of the genus Poecilia (Teleostei:Poeciliidae) and designated Poecilia linkage group I. These two loci were shown to assort independently from six other informative markers (peptidase S, malate dehydrogenase 2 [soluble], mannose phosphate isomerase, parvalbumin 2, phosphoglucomutase, and glyceraldehyde-3-phosphate dehydrogenase 2) within the limits of the data obtained. Data for the linkage analyses were generated by scoring starch-gel electrophoretic phenotypes of the eight loci in reciprocal backcross hybrids obtained from matings between Poecilia perugiae and P. vittata. The linkage chi 2 for G6PD-PGD locus pairs was significant (P less than 0.001) in all reciprocal backcross hybrid broods (22.7% recombinants in the combined data), indicating linkage in both parental species. The linkage of G6PD and PGD in gene maps of the poeciliid genera Xiphophorus and Poeciliopsis documents homology of this linkage within the family. Linkages in salmonid and centrarchid fishes suggest conservation of this linkage group in most or all teleosts. The six additional indpendently assorting loci have been assigned to independent linkage groups in Xiphophorus; thus, no example of poeciliid linkage group divergence has yet been identified.     

Isoenzyme studies in one Brazilian and two Venezuelan strains of Schistosoma mansoni.

1. Enzyme polymorphism, analyzed by starch gel electrophoresis, was found to be zero for acid phosphatase, phosphoglucomutase, phosphoglucose isomerase, glucose 6-phosphate dehydrogenase, lactate dehydrogenase, malate dehydrogenase and malic enzyme, in one Brazilian and two Venezuelan strains of Schistosoma mansoni. 2. All loci studied were monomorphic within strains, but the isoenzymic patterns were, however, different among the strains. 3. Results suggest a drastic loss of the genetic variability usually found in natural populations.     

Sheep gene mapping: additional DNA markers included (CASB, CASK, LALBA, IGF-1 and AMH).

DNA extracted from 25 hamster-sheep hybrid cell lines was subjected, after Southern blotting, to hybridization with CASB, CASK, LALBA, IGF-1 and AMH cDNA probes. CASB and CASK segregated together and IGF-1 and LALBA were found syntenic with the LDHB-PEPB-TPI-GAPD-SHMT-KRTB group. No other synteny was observed with any of the previously described groups using the same hybrid cell panel. Gene nomenclature: ACO 1: aconitase 1 (soluble); ADA: adenosine deaminase; AMH: antiMüllerian hormone; ARA 1: murine sarcoma 3611 viral (v-raf) oncogene homologue 1; CASB: beta-casein; CASK: kappa-casein; ENO 1: enolase 1 (alpha); G6PD: glucose-6-phosphate dehydrogenase; GALA (or GLA): glactosidase (alpha); GAPD: glyceraldehyde -3- phosphate dehydrogenase; GPI: glucose phosphate isomerase; GSR: glutathione reductase; HBG: haemoglobin gamma; HPRT: hypoxanthine phosphoribosyl transferase; IDH 1: isocitrate dehydrogenase 1 (soluble); IGF-1: insulin growth factor 1; ITPA: inosine triphosphatase; KRTA: keratin (acid); KRTB: keratin (basic); LALBA: alpha-lactalbumin; LDHA: lactate dehydrogenase A; LDHB: lactate dehydrogenase B; MDH 2: malate dehydrogenase NAD (soluble); ME 1: malic enzyme (soluble); MPI: mannose phosphate isomerase; NP: nucleoside phosphorylase; OLA: ovine leucocyte antigen; OTC: ornitine carbamoyltransferase; PAIS: phosphoribosyl amino imidazole synthetase; PEPA, PEPB, PEPC: peptidase A, B, C; PGD: phospho gluconate dehydrogenase; PGK: phosphoglycerate kinase; PGM 3: phospho glucomutase 3; PKM 2: pyruvate kinase (muscle); PLP: proteolipid protein; PRGS: phosphoribosyl glycinamide synthetase; RCP: red cone pigment; SHMT: serine hydroxymethyl transferase; SOD 1: superoxide dismutase 1 (soluble); SYN 1: synapsin 1; TPI l: triose phosphate isomerase 1.     

The Genetics of α-Hydroxyacid Oxidase and Alcohol Dehydrogenase in the Mouse: Evidence for Multiple Gene Loci and Linkage between Hao-2 and Adh-3

Electrophoretic polymorphisms for stomach alcohol dehydrogenase (ADH-C2) and kidney L-alpha-hydroxyacid oxidase (HAOX-B4) have been identified in an Asian subspecies of mouse, Musmusculus castaneous. These variants are inherited in a normal Mendelian fashion with two alleles in each case showing codominant expression. The structural gene loci for those enzymes (Adh-3 and Hao-2, respectively) are apparently linked (17.6% recombinants) in this organism, whereas the multiple gene loci for HAOX, Hao-1 (encoding the A4 liver isozyme) and Hao-2, exhibited independent segregation and are unlinked (50% recombinants). Evidence is presented for 3 ADH loci: ADH-1, encoding liver ADH-A2 which exhibits high activity with ethanol (SELANDER, HUNT and YANG 1969; ADH-2, liver and stomach ADH-B2 using 2-hexene-1-ol as substrate; and Adh-3, stomach ADH-C2 using both benzyl alcohol and 2-hexene-1-ol as substrate.     

Isozyme variation and the reproductive biology of Hydrocharis morsus-ranae L. (Hydrocharitaceae)

Electro-phoretically detectable isozyme variation was studied for 17 enzyme systems in several N American populations of the introduced aquatic plant Hydrocharis morsus-ranae and in two European populations. Twenty-nine loci were inferred from progeny, adult and turion enzyme banding patterns with 28 of these loci homozygous in all individuals studied. Malate dehydrogenase-1 (MDH-1) was the only locus which could be interpreted as multi-allelic and heterozygous. Twenty-seven of 76 seedlings assayed showed an age specific expression for an alcohol dehydrogenase locus (ADH-2) never seen in adults or turions. Since all adults sampled were phenotypically identical at all loci assayed, it is possible that only one isozyme genotype of this species is present in N America. European turion data further indicated that the populations studied were identical to N American plants sampled at all loci except EST. Therefore, although H. morsus-ranae is dioecious, outcrossing appears to involve substantial inbreeding. Connections between extensive inbreeding and the failure of effective sexual reproduction are considered.     

High activity of an unstable form of glucose phosphate isomerase in the mouse

Quantitative electrophoretic studies of the three allozymes of glucose phosphate isomerase (GPI-1) produced byGpi-1s ^a/Gpi-1s^c heterozygous mice revealed two opposing influences on GPI-1 activity. First, the GPI-1 AC heterodimer is less stable than GPI-1 AA but more stable than the GPI-1 CC homodimer. Second, a genetic determinant that maps close to or within theGpi-1s structural gene causes elevated activity of GPI-1 AC and probably also GPI-1 CC dimers. The relative lability of these allozymes masks this elevated activity in some tissues but the effect is probably ubiquitous. The significance of these observations is discussed.This study was begun while JDW was at the MRC Radiobiology Unit and continued at the Department of Obstetrics and Gynaecology of the University of Edinburgh, where it was supported, in part, by a grant from the Moray Endowment Fund.     

Non-additive inheritance of glucose phosphate isomerase activity in mice heterozygous at the Gpi-1s structural locus

The activity of blood glucose phosphate isomerase (GPI-1) in mice heterozygous for various alleles at the Gpi-1s structural locus (heterozygotes a/b, a/c and b/c) was significantly higher than expected, on the basis of additive inheritance, from the levels in parental homozygotes. Moreover, the GPI-1 activity was higher in a/b heterozygotes than in either parent (heterosis). Studies of heat stability with kidney homogenates revealed that the relative stabilities of GPI-1 dimers was AA greater than AB greater than BB greater than AC greater than or equal to BC greater than CC. Differences in dimer stabilities in vivo would affect the total GPI-1 levels in heterozygotes and could account for non-additive inheritance but would be insufficient to explain heterosis for GPI-1 activity. Other possible contributing factors include unequal production or stability of monomers, or higher catalytic activity of heterodimers. Monomers could also associate non-randomly but this would not be sufficient to explain heterosis. It is clear that non-additive inheritance patterns may be produced by variants of either structural or regulatory genes.